Sphygmomanometer, blood pressure measurement method, and device

ABSTRACT

A sphygmomanometer includes a main body mounted with a pump, a belt, and a cuff structure. The cuff structure having a band shape is disposed facing an inner circumferential surface of the belt in a freely separable manner from the inner circumferential surface of the belt. One end of the cuff structure is attached to the main body. The cuff structure includes a bag-shaped pressure cuff that extends along a circumferential direction of a measurement target site, a bag-shaped sensing cuff that extends in the circumferential direction across an artery passing portion of the measurement target site, and a back plate that is inserted between the pressure cuff and the sensing cuff. A blood pressure is calculated based on a pressure of a pressure transmission fluid contained in the sensing cuff.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application of International Application No.PCT/JP2017/042085, with an International filing date of Nov. 22, 2017,which claims priority of Japanese Patent Application No. 2016-256022filed on Dec. 28, 2016, the entire content of which is herebyincorporated by reference.

TECHNICAL FIELD

The present invention relates to a sphygmomanometer, and moreparticularly to a sphygmomanometer including a belt attached around ameasurement target site and a main body mounted with a pump. The presentinvention also relates to a blood pressure measurement method formeasuring a blood pressure at a measurement target site. Furthermore,the present invention relates to a device including a blood pressuremeasurement function.

BACKGROUND ART

Conventionally, as this type of sphygmomanometer, for example, asdisclosed in Patent Literature 1 (JP 2013-215397 A), there is known asphygmomanometer having a blood pressure measurement cuff wound around awrist as a measurement target site and a main body integrally attachedto the cuff. In this sphygmomanometer, a pressure in an air bag forpressurization contained in the cuff is detected by a pressure sensormounted on the main body. At the time of blood pressure measurement,with the cuff attached around the wrist, air for pressurization issupplied from the pump mounted on the main body to the air bag to pressthe artery of the wrist. Based on the output of the pressure sensor, ablood pressure measurement value is calculated by an oscillometricmethod.

SUMMARY OF INVENTION

Due to the recent health-conscious trend, there is a growing need formeasuring blood pressure with the sphygmomanometer (blood pressuremeasurement cuff) constantly attached to the wrist. In that case, it isdesirable to make the width direction dimension of the cuff (thedimension in the direction along the longitudinal direction of thewrist) as small as possible from the viewpoints of appearance, wearingcomfort, and the like.

However, in the sphygmomanometer described above, if the width directiondimension of the cuff is set to be as small as, for example, 25 mm, thecuff (air bag) greatly inflates in the thickness direction whenpressurized, and its cross section becomes nearly a circular shape froma flat elliptical shape, thereby causing press loss to occur. That is,the pressure in the cuff is higher than the pressure applied to theartery of the wrist. As a result, the blood pressure measurement valueis observed higher than the actual blood pressure, and there is aproblem that a measurement error becomes large.

Therefore, the present applicant has recently proposed asphygmomanometer including a pressure cuff having a band shape and thatis wound around the measurement target site and receives a supply ofpressurization fluid to press the measurement target site, and a sensorassembly that is disposed on an inner circumferential surface of thepressure cuff at a portion of the measurement target site to face theartery and, separately from the pressure cuff, detects a pressureapplied by the pressure cuff to an artery passing portion of themeasurement target site (Japanese Patent Application No. 2016-106622).

In this sphygmomanometer, the sensor assembly detects the pressureitself applied to an artery passing portion of the measurement targetsite. Accordingly, the blood pressure can be accurately measured, evenif the pressure cuff greatly inflates in the thickness direction whenpressurized and press loss occurs as a result of setting the widthdirection dimension of the cuff to be small (about 25 mm for example).

However, in this proposed sphygmomanometer, the sensor assembly islocally disposed so as to correspond only to the radial artery of themeasurement target site in the longitudinal direction of the pressurecuff (corresponding to the circumferential direction of the wrist).Therefore, when the user actually attaches the sphygmomanometer (cuff)on the wrist, the sensor assembly is attached at a position displacedfrom the radial artery as a result of the cuff being slightly displacedin the circumferential direction of the wrist. In that case, there is aproblem that the sensor assembly is not capable of acquiring a pulsewave signal appropriately and a blood pressure measurement value varieswith respect to the actual blood pressure.

Therefore, an object of the present invention is to provide asphygmomanometer, a blood pressure measurement method, and a device thatare capable of accurately measuring a blood pressure while permitting acertain degree of displacement of the cuff in the circumferentialdirection of the measurement target site.

In order to solve the problem described above, a sphygmomanometer of thepresent disclosure includes:

a main body mounted with a pump;

a belt that extends from the main body and is to be attached around ameasurement target site; and

a cuff structure having a band shape, and that is disposed facing aninner circumferential surface of the belt and has one end attached tothe main body in a freely separable manner from the innercircumferential surface of the belt,

wherein the cuff structure includes

a bag-shaped pressure cuff that extends along a circumferentialdirection of the measurement target site so as to receive a supply ofpressurization fluid to press the measurement target site,

a sensing cuff that is configured in a bag shape so as to be capable ofcontaining pressure transmission fluid, is disposed along an innercircumferential surface of the pressure cuff, and extends in thecircumferential direction across an artery passing portion of themeasurement target site, and

a back plate that is inserted between the pressure cuff and the sensingcuff, extends along the circumferential direction of the measurementtarget site, and transmits a pressing force from the pressure cuff tothe sensing cuff, and

the sphygmomanometer includes

a pressurization control unit that performs control of supplying thepressurization fluid from the pump to the pressure cuff to press themeasurement target site, and

a blood pressure calculation unit that calculates a blood pressure basedon a pressure of the pressure transmission fluid contained in thesensing cuff.

As for the “belt” that “extends from the main body” in the presentspecification, the main body and the belt may be integrally molded, orthe main body and the belt may be formed separately from each other andthe belt may be attached to the main body. Furthermore, as for the beltitself, a first belt portion that extends in one direction from the mainbody and a second belt portion that extends in the other direction fromthe main body may be fastened or released by a clasp, or may be coupledby an openable buckle. The “inner circumferential surface” of the beltrefers to a surface that is on the inner circumferential side with thebelt being attached around the measurement target site. Similarly, the“inner circumferential surface” of the pressure cuff refers to a surfacethat is on the inner circumferential side with the pressure cuff beingattached around the measurement target site.

In addition, the “pressure transmission fluid” may be contained in thesensing cuff at the manufacturing stage of the sphygmomanometer, or mayalso be contained in the sensing cuff and discharged from the sensingcuff each time the blood pressure is measured.

Also, the “fluid” for pressurization or pressure transmission istypically air, but it may be other gas or liquid.

In another aspect, a blood pressure measurement method of the presentdisclosure is a method for measuring a blood pressure at a measurementtarget site, including:

a main body mounted with a pump;

a belt that extends from the main body and is to be attached around ameasurement target site; and

a cuff structure having a band shape, and that is disposed facing aninner circumferential surface of the belt and has one end attached tothe main body in a freely separable manner from the innercircumferential surface of the belt,

wherein the cuff structure includes

a bag-shaped pressure cuff that extends along a circumferentialdirection of the measurement target site so as to receive a supply ofpressurization fluid to press the measurement target site, a sensingcuff that is configured in a bag shape so as to be capable of containingpressure transmission fluid, is disposed along an inner circumferentialsurface of the pressure cuff, and extends in the circumferentialdirection across an artery passing portion of the measurement targetsite, and

a back plate that is inserted between the pressure cuff and the sensingcuff, extends along the circumferential direction of the measurementtarget site, and transmits a pressing force from the pressure cuff tothe sensing cuff,

the blood pressure measurement method comprising:

performing control of supplying the pressurization fluid from the pumpto the pressure cuff to press the measurement target site, and

calculating a blood pressure based on a pressure of the pressuretransmission fluid contained in the sensing cuff

In another aspect, a device of the present disclosure is a devicecomprising a main body mounted with blood pressure measurement elements,

wherein the blood pressure measurement elements include

a pump mounted to the main body,

a belt that extends from the main body and is to be attached around ameasurement target site, and

a cuff structure having a band shape, and that is disposed facing aninner circumferential surface of the belt and has one end attached tothe main body in a freely separable manner from the innercircumferential surface of the belt,

the cuff structure includes

a bag-shaped pressure cuff that extends along a circumferentialdirection of the measurement target site so as to receive a supply ofpressurization fluid to press the measurement target site,

a sensing cuff that is configured in a bag shape so as to be capable ofcontaining pressure transmission fluid, is disposed along an innercircumferential surface of the pressure cuff, and extends in thecircumferential direction across an artery passing portion of themeasurement target site, and

a back plate that is inserted between the pressure cuff and the sensingcuff, extends along the circumferential direction of the measurementtarget site, and transmits a pressing force from the pressure cuff tothe sensing cuff, and

the device includes

a pressurization control unit that performs control of supplying thepressurization fluid from the pump to the pressure cuff to press themeasurement target site, and

a blood pressure calculation unit that calculates a blood pressure basedon a pressure of the pressure transmission fluid contained in thesensing cuff.

The “device” of the present disclosure widely includes a device having ablood pressure measurement function, and may be configured as, forexample, a wristwatch-type wearable device such as a smart watch.

BRIEF DESCRIPTION OF DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1 shows an appearance of a sphygmomanometer according to anembodiment of the present invention as viewed obliquely, with a beltfastened.

FIG. 2 shows an appearance of the sphygmomanometer as viewed obliquely,with a belt released.

FIG. 3B shows a planar layout when a cuff structure in FIG. 2 isunfolded with its inner circumferential surface at the forefront. FIG.3A shows a cross section taken along line IIIA-IIIA in FIG. 3B.

FIG. 4A is an enlarged view showing a vicinity of a tip end portion of acuff structure in FIG. 3B. FIG. 4B shows a cross section taken alongline IVB-IVB in FIG. 4A.

FIG. 5A shows a planar layout of a pressure cuff included in the cuffstructure. FIG. 5B shows a planar layout of a back plate included in thecuff structure, with the pressure cuff as a background.

FIG. 6 shows a back side of a main body of the sphygmomanometer asviewed obliquely.

FIG. 7 shows a back side of the main body together with a curlerincluded in the cuff structure described above, in a disassembled statewhere a back lid is detached.

FIG. 8 shows an inside of the main body as viewed obliquely from above.

FIG. 9 shows an inside of the main body as viewed obliquely from below.

FIG. 10 shows a block configuration of a control system of thesphygmomanometer.

FIG. 11 shows an operation flow when a user performs blood pressuremeasurement using the sphygmomanometer as a blood pressure measurementmethod according to an embodiment of the present invention.

FIG. 12 shows a flow of processing in which a user attaches thesphygmomanometer on the left wrist.

FIG. 13A is a perspective view showing a manner in which a user attachesa cuff structure to the left wrist using the right hand.

FIG. 13B is a perspective view showing a manner in which a usercollectively surrounds the left wrist and the cuff structure with a beltusing the right hand.

FIG. 13C is a perspective view showing a manner in which thesphygmomanometer is attached to the user's left wrist.

FIG. 14 shows a cross section perpendicular to the left wrist, with thesphygmomanometer attached to the user's left wrist.

FIG. 15A shows a cross section (corresponding to a cross section takenalong line XVA-XVA in FIG. 14 ) of a portion through which a tendon of aleft wrist passes, in a pressurized state.

FIG. 15B shows a cross section (corresponding to a cross section takenalong line XVB-XVB in FIG. 14 ) of a portion through which a radialartery of a left wrist passes, in a pressurized state.

FIG. 16 is a view exemplifying a pressure Pc of a sensing cuff and apulse wave signal Pm which are detected by a second pressure sensormounted on the main body.

FIG. 17 shows a blood pressure measurement error when water is used as apressure transmission fluid contained in the sensing cuff and an amountof water contained in the sensing cuff is set variably.

FIG. 18 is a scatter diagram showing a relationship between a referenceblood pressure value and a blood pressure measurement error in a casewhere an amount of water contained in the sensing cuff is set variablyto “small amount of water”=0.16 ml, “appropriate amount”=0.3 ml, and“large amount of water”=0.8 ml for a plurality of users.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the drawings.

(Configuration of Sphygmomanometer)

FIG. 1 shows an appearance of a sphygmomanometer according to anembodiment of the present invention (indicated by a reference numeral 1as a whole) as viewed obliquely, with a belt 2 fastened. FIG. 2 showsthe appearance of the sphygmomanometer 1 as viewed obliquely, with thebelt 2 released.

As shown in these figures, the sphygmomanometer 1 roughly includes amain body 10, the belt 2 which extends from the main body 10 and is tobe attached around a measurement target site (in this example, as shownin FIG. 13C described later, a left wrist 90 is assumed to be themeasurement target site), and a cuff structure 20 that has a band shapeand has one end 20 f attached to the main body 10. The dimension of thebelt 2 in a width direction X is set to 29 mm in this example. Thethickness of the belt 2 is set to 2 mm in this example.

In this example, the main body 10 has a substantially short cylindricalcase 10B, a circular glass 10A attached to an upper portion (in FIGS. 1and 2 ) of the case 10B, and a back lid 10C (see FIG. 6 ) attached to alower portion of the case 10B. Side surfaces of the case 10B areprovided with left and right (in FIGS. 1 and 2 ) pairs of protrudinglugs 10B1 and 10B2 and 10B3 and 10B4 for attaching the belt 2,respectively, in an integral manner.

In a glass 10A of the upper portion of the case 10B, an indicator 50serving as a display screen is provided. The side surface of the frontside (in FIGS. 1 and 2 ) of the main body 10 is provided with ameasurement switch 52A for instructing start or stop of blood pressuremeasurement, a home switch 52B for causing a display screen of theindicator 50 to return to a predetermined home screen, and a recordingcall switch 52C for performing an instruction of causing the indicator50 to display measurement records such as past blood pressure andactivity amount (these switches are collectively referred to as anoperation unit 52). Blood pressure measurement elements including a pump30 (to be described in detail later) are mounted to the inside of themain body 10. In this example, the sphygmomanometer 1 includes functionsof an activity amount meter and a pulsimeter. That is, thesphygmomanometer 1 is configured as a multifunctional device having anaspect of a wristwatch-type wearable device. The main body 10 is formedto be small and thin so as not to interfere with the daily activities ofthe user.

As can be clearly seen from FIG. 2 , the belt 2 includes a band-shapedfirst belt portion 3 which extends from the main body 10 to one side(right side in FIG. 2 ) in one direction, and a band-shaped second beltportion 4 which extends from the main body 10 to the other side (leftside in FIG. 2 ) in the one direction. A basal portion 3 e of the firstbelt portion 3 on a side closer to the main body 10 is attachedrotatably to the lugs 10B1 and 10B2 of the main body 10 via a couplingrod 7 (publicly known spring rod) that extends in the width direction Xof the belt, as shown by a double arrow A. Similarly, a basal portion 4e of the second belt portion 4 on a side closer to the main body 10 isattached rotatably to the lugs 10B3 and 10B4 of the main body 10 via acoupling rod 8 (publicly known spring rod) that extends in the widthdirection X of the belt, as shown by a double arrow B.

A clasp 5 is attached to a tip end portion 3 f of the first belt portion3 on the side far from the main body 10. The clasp 5 is of a publiclyknown type and includes a substantially U-shaped frame 5A, a prong 5B,and a coupling rod 5C that extends in the width direction X of the belt.The frame 5A and the prong 5B are each rotatably attached to the tip endportion 3 f of the first belt portion 3 on the side far from the mainbody 10 as indicated by a double arrow C via the coupling rod 5C.Ring-shaped belt holding portions 6A and 6B are integrally providedbetween the tip end portion 3 f and the basal portion 3 e of the firstbelt portion 3 at a predetermined position in the longitudinal directionof the first belt portion 3 (corresponding to a circumferentialdirection Y of the left wrist 90). An inner circumferential surface 3 aof the first belt portion 3 does not protrude to the innercircumferential side at the locations of the belt holding portions 6Aand 6B, and is formed to be generally flat (locally, although curved asa whole). Thus, the belt 2 uniformly surrounds and restrains the outercircumferential side of the cuff structure 20.

A plurality of small holes 4 w, 4 w, . . . are formed in the second beltportion 4 between the basal portion 4 e and a tip end portion 4 f on theside far from the main body 10 so as to penetrate the second beltportion 4 in the thickness direction. When the first belt portion 3 andthe second belt portion 4 are fastened, a portion continuing to the tipend portion 4 f of the second belt portion 4 is passed through the frame5A of the clasp 5, and the prong 5B of the clasp 5 is inserted into anyone of the plurality of small holes 4 w, 4 w, . . . of the second beltportion 4. Due to this, as shown in FIG. 1 , the first belt portion 3and the second belt portion 4 are fastened.

In this example, the first belt portion 3 and the second belt portion 4constituting the belt 2 are made of a plastic material that hasflexibility in the thickness direction and exhibits substantially nostretchability in the longitudinal direction (corresponding to thecircumferential direction Y of the left wrist 90). This allows the belt2 to be easily wrapped around and restrain the outer circumferentialside of the cuff structure 20 at the time of attachment, and to help topress the left wrist 90 at the time of blood pressure measurement to bedescribed later. The first belt portion 3 and the second belt portion 4may be made of a leather material. While the frame 5A and the prong 5Bthat constitute the clasp 5 are made of a metal material in thisexample, the frame 5A and the prong 5B may be made of a plasticmaterial.

As shown in FIG. 2 , the cuff structure 20 includes a curler 24 disposedat the outermost circumference, a pressure cuff 23 disposed along theinner circumferential surface of the curler 24, a back plate 22 as areinforcing plate disposed along the inner circumferential surface ofthe pressure cuff 23, and a sensing cuff 21 disposed along the innercircumferential surface of the back plate 22.

FIG. 3B shows a planar layout when the cuff structure 20 in FIG. 2 isunfolded with its inner circumferential surface 20 a at the forefront.FIG. 3A shows a cross section taken along line IIIA-IIIA in FIG. 3B.FIG. 4A is an enlarged view showing a vicinity of a tip end portion ofthe cuff structure 20 in FIG. 3B. FIG. 4B shows a cross section takenalong line IVB-IVB in FIG. 4A. FIG. 5A shows a planar layout of thepressure cuff 23. FIG. 5B shows a planar layout of the back plate 22,with the pressure cuff 23 as a background.

As shown in FIGS. 3A and 3B, the curler 24, the pressure cuff 23, theback plate 22, and the sensing cuff 21 each have a band shape elongatedin one direction (Y direction). In this example, the dimension of thecurler 24 in the width direction X is set to W1=28 mm, the dimension ofthe pressure cuff 23 (excluding the edge portions on both sides welded)in the width direction X is set to W2=25 mm, the dimension of the backplate 22 in the width direction X is set to W3=23 mm, and the dimensionof the sensing cuff 21 in the width direction X (excluding the edgeportions on both sides welded) is set to W4=15 mm. Also, the dimensionof the curler 24 in a longitudinal direction Y (excluding a basalportion 24 f attached to the main body 10) is set to L1=148 mm, thedimension of the pressure cuff 23 in the longitudinal direction Y is setto L2=140 mm, the dimension of the back plate 22 in the longitudinaldirection Y is set to L3=114 mm, and the dimension of the sensing cuff21 in the longitudinal direction Y is set to L4=110 mm.

As can be seen from FIGS. 4A and 4B, the sensing cuff 21 includes afirst sheet 21A on the side in contact with the left wrist 90 and asecond sheet 21B facing the first sheet 21A, and circumferentialportions 21 m of the first and second sheets 21A and 21B are in closecontact with each other by welding to form a bag shape. In this example,as shown in FIG. 4B, slacks 21 r and 21 r that extend along thelongitudinal direction Y of the sensing cuff 21 in a natural state areprovided at a location continuing to the edge portions 21 m and 21 m onboth sides of the sensing cuff 21 in the width direction X. As shown inFIG. 4A, the slack 21 r that extends along the width direction X of thesensing cuff 21 in a natural state is provided at a location continuingto the edge portion 21 m (only the tip end side is shown in FIG. 4A onboth sides of the sensing cuff 21 in the longitudinal direction Y of thefirst sheet 21A. Such a slack 21 r can be formed by a publicly knownmethod, for example, when the circumferential portions 21 m of the firstand second sheets 21A and 21B are welded together so as to be broughtinto close contact. As can be seen from FIGS. 3A and 3B, an end portionon the basal side (+Y side) of the sensing cuff 21 in the longitudinaldirection Y is attached with a flexible tube 38 for supplying a pressuretransmission fluid (air in this example) to the sensing cuff 21 ordischarging a pressure transmission fluid from the sensing cuff 21. Thematerial of the first and second sheets 21A and 21B is made of astretchable polyurethane sheet (thickness t=0.15 mm) in this example.The inner circumferential surface 20 a of the cuff structure 20 isconstituted by the first sheet 21A of the sensing cuff 21.

As can be seen from FIGS. 4A and 4B, the pressure cuff 23 includes twofluid bags 23-1 and 23-2 stacked in the thickness direction. Each of thefluid bags 23-1 and 23-2 is formed by facing two stretchablepolyurethane sheets (thickness t=0.15 mm) and welding theircircumferential portions 23 m 1 and 23 m 2. As shown in FIG. 5A, thedimension of the fluid bag 23-1 on the inner circumferential side in thelongitudinal direction Y is set to be slightly smaller than thedimension (L2) of the fluid bag 23-2 on the outer circumferential sidein the longitudinal direction Y. An end portion on the basal side (+Yside) of the fluid bag 23-2 on the outer circumferential side in thelongitudinal direction Y is attached with a flexible tube 39 forsupplying a pressure transmission fluid (air in this example) to thepressure cuff 23 or discharging a pressure transmission fluid from thepressure cuff 23. A plurality of (four in this example) through holes 23o, 23 o, . . . are formed between the fluid bag 23-1 on the innercircumferential side and the fluid bag 23-2 on the outer circumferentialside that is adjacent thereto. This allows the pressurization fluid (airin this example) to flow between the two fluid bags 23-1 and 23-2through the through holes 23 o, 23 o, . . . Thus, when the pressure cuff23 receives the supply of pressurizing fluid from the main body 10 sidethrough the flexible tube 39 in the attached state, the two stackedfluid bags 23-1 and 23-2 inflate to press the left wrist 90 as a whole.

The back plate 22 is made of a plate-shaped resin (polypropylene in thisexample) having a thickness of about 1 mm in this example. As can beseen from FIGS. 3A and 3B, the back plate 22 extends in a band shapebeyond the length of the sensing cuff 21 in the longitudinal direction Y(corresponding to the circumferential direction of the left wrist 90).Accordingly, the back plate 22 acts as a reinforcing plate, and cantransmit the pressing force from the pressure cuff 23 to the entire areaof the sensing cuff 21 in the longitudinal direction Y (corresponding tothe circumferential direction of the left wrist 90). As can be seen fromFIGS. 4A and 5B, the inner circumferential surface 22 a and the outercircumferential surface 22 b of the back plate 22 are provided with aplurality of grooves 22 d 1 and 22 d 2 with V-shaped or U-shaped crosssections that extend in the width direction X and are parallel to andspaced apart from each other in the longitudinal direction Y. In thisexample, the grooves 22 d 1 and 22 d 2 are provided at the same positioncorresponding to each other between the inner circumferential surface 22a and the outer circumferential surface 22 b of the back plate 22. As aresult, the back plate 22 becomes thinner and easily bent at thelocations of the grooves 22 d 1 and 22 d 2 compared to other locations.Accordingly, the back plate 22 does not obstruct the cuff structure 20from being bent along the circumferential direction Y of the left wrist90 when the user collectively surrounds the left wrist 90 and the cuffstructure 20 with the belt 2 (step S22 in FIG. 12 described later) atthe time of attaching.

The curler 24 is made of a resin plate (polypropylene in this example)having a thickness of about 1 mm and having a certain degree offlexibility and hardness in this example. As can be seen from FIGS. 3Aand 3B, when unfolded, the curler 24 extends in a band shape beyond thelength of the pressure cuff 23 in the longitudinal direction Y(corresponding to the circumferential direction of the left wrist 90).As shown in FIG. 7 , the curler 24 has a curved shape along thecircumferential direction Y surrounding the left wrist 90 in a naturalstate. Due to this, the shape of the cuff structure 20 in a naturalstate is kept curved along the circumferential direction Y of the leftwrist 90 as shown in FIG. 2 .

At the circumferential portion of the inner circumferential surface 22 aof the back plate 22 and the circumferential portion of the innercircumferential surface 24 a of the curler 24, circular arcs 22 r and 24r curved outwards from the measurement target site (left wrist 90 inthis example) are formed respectively. This prevents the user fromfeeling discomfort due to attachment of the cuff structure 20.

As shown in FIG. 6 , the back lid 10C is provided on the back side ofthe main body 10. The back lid 10C has four through holes 10C1, 10C2,10C3, and 10C4 and is fixed to the back side of the case 10B withunillustrated screws through the through holes 10C1, 10C2, 10C3, and10C4. A portion to be hidden by the basal portion 3 e of the first beltportion 3 on the side surface of the case 10B is provided with filteredintake and exhaust holes 10Bo, 10Bo, . . . (the same is true for aportion hidden by the basal portion 4 e of the second belt portion 4).This allows air to flow between the inside and outside of the case 10Bwhile realizing a life waterproofing function.

FIG. 7 shows the back side of the main body 10 together with the curler24, in a disassembled state where the back lid 10C is detached. In thecase 10B of the main body 10, an inner case member 11 for mounting bloodpressure measurement elements is contained. On the back side of theinner case member 11, an annular groove 11 d is formed so as to surrounda protrusion 11 p. A ring 24 o having a shape corresponding to theannular groove 11 d is formed at the basal portion 24 f of the curler24. When assembling the main body 10, the ring 24 o of the basal portion24 f of the curler 24 is fitted into the annular groove 11 d of theinner case member 11 (at the same time, the ring 24 o is fitted into theprotrusion 11 p of the inner case member 11). Then the basal portion 24f of the curler 24 is clamped between the back side of the inner casemember 11 and the back lid 10C of the main body 10 in a state of beingoverlapped with two flow path formation members (a first flow pathformation member 390 and a second flow path formation member 380) to bedescribed later.

As a result, as shown in FIG. 2 , the one end 20 f of the cuff structure20 (the basal portion 24 f of the curler 24) is attached to the mainbody 10. The other end 20 e of the cuff structure 20 (a tip end portion24 e of the curler 24) is a free end. As a result, the cuff structure 20faces the inner circumferential surfaces 3 a and 4 a of the belt 2 andis freely separable from the inner circumferential surfaces 3 a and 4 a.

When the cuff structure 20 is attached to the main body 10 in thismanner, the one end 20 f of the cuff structure 20 is reliably held bythe main body 10. At the time of maintenance service, the cuff structure20 can be replaced with respect to the main body 10 regardless of thebelt 2 by opening the back lid 10C of the main body 10. Also, thedimension of the cuff structure 20 in the longitudinal direction Y(corresponding to the circumferential direction of the left wrist 90)can be set to the optimum dimension regardless of the belt 2.

Note that in the sphygmomanometer 1, the main body 10 and the belt 2 areformed separately from each other and the belt 2 is attached to the mainbody 10, and therefore, during maintenance service, the belt 2 can alsobe replaced with respect to the main body 10 regardless of the cuffstructure 20.

The first flow path formation member 390 shown in FIG. 7 includes twosheet plates 391 and 392 that expand in a thin plate shape facing eachother and a spacer portion 393 that keeps the sheet plates 391 and 392with a predetermined interval (0.7 mm in this example). Similarly, thesecond flow path formation member 380 includes two sheet plates 381 and382 that expand in a thin plate shape facing each other and a spacerportion 383 that keeps the sheet plates 381 and 382 with a predeterminedinterval. The sheet plate 381 and the spacer portion 383 are shown inFIG. 9 (In FIG. 9 , the sheet plates 392 and 382 on the side far fromthe inner case member 11 are not illustrated for the sake of easyunderstanding. FIG. 9 will be described later.). Laterally oriented pins390 p and 380 p are integrally attached to the end portion of the firstflow path formation member 390 and the end portion of the second flowpath formation member 380, respectively, so as to allow fluid to flow.When the cuff structure 20 including the curler 24 is attached to themain body 10, the flexible tube 39 from the pressure cuff 23 isconnected to the first flow path formation member 390 via the laterallyoriented pin 390 p. The flexible tube 38 from the sensing cuff 21 isconnected to the second flow path formation member 380 via the laterallyoriented pin 380 p.

The first flow path formation member 390 and the second flow pathformation member 380 are formed by integrally molding elastomer in thisexample. The thickness dimension of the first flow path formation member390 and the second flow path formation member 380 is set to 1.2 mm inthis example.

FIG. 10 shows a block configuration of the control system of thesphygmomanometer 1. As blood pressure measurement elements forperforming blood pressure measurement in addition to the indicator 50and the operation unit 52 described above, the main body 10 of thesphygmomanometer 1 is mounted with a main CPU (Central Processing Unit)100 as a control unit, a sub CPU 101, a memory 51 as a storage unit, anacceleration sensor 54, a communication unit 59, a battery 53, a firstpressure sensor 31 for detecting pressure of the pressure cuff 23, asecond pressure sensor 32 for detecting pressure of the sensing cuff 21,a pump 30, an open/close valve 33, and a pump drive circuit 35 thatdrives the pump 30. The main CPU 100 mainly controls the operation ofthe entire sphygmomanometer 1, and the sub CPU 101 mainly controls anoperation of an air system. Hereinafter, for the sake of simplicity, themain CPU 100 and the sub CPU 101 will be simply referred to as the CPU100 in combination.

The indicator 50 is configured by an LCD (Liquid Crystal Display) inthis example and, in accordance with a control signal from the CPU 100,displays information on blood pressure measurement such as a bloodpressure measurement result and other information. The indicator 50 isnot limited to an organic EL display but may be the indicator 50 ofanother type such as an organic EL (Electro Luminescence) display. Theindicator 50 may include an LED (Light Emitting Diode).

As described above, the operation unit 52 includes the measurementswitch 52A for instructing start or stop of blood pressure measurement,the home switch 52B for causing a display screen of the indicator 50 toreturn to a predetermined home screen, and the recording call switch 52Cfor performing an instruction of causing the indicator 50 to displaymeasurement records such as past blood pressure and activity amount. Inthis example, these switches 52A to 52C are push-type switches, and theswitches 52A to 52C input operation signals to the CPU 100 in accordancewith an instruction by the user such as start or stop of blood pressuremeasurement. The operation unit 52 is not limited to the push-typeswitch but may be, for example, a pressure-sensitive (resistive) orproximity (electrostatic capacitive) touch panel-type switch. Inaddition, an unillustrated microphone may be provided to input aninstruction for blood pressure measurement start by the user's voice.

The memory 51 non-transitorily stores data of a program for controllingthe sphygmomanometer 1, data used to control the sphygmomanometer 1,setting data for setting various functions of the sphygmomanometer 1,data of measurement results of blood pressure values, and the like. Thememory 51 is also used as a work memory or the like when a program isexecuted.

The CPU 100 executes various functions as a control unit in accordancewith a program for controlling the sphygmomanometer 1 stored in thememory 51. For example, when executing a blood pressure measurementfunction, the CPU 100 performs control to drive the pump 30 and theopen/close valve 33 based on signals from the first pressure sensor 31and the second pressure sensor 32 in response to an instruction of startof blood pressure measurement from the measurement switch 52A of theoperation unit 52. The CPU 100 performs control to calculate a bloodpressure value, a pulse, and the like based on a signal from the secondpressure sensor 32.

The acceleration sensor 54 is configured by a three-axis accelerationsensor integrated in the main body 10. The acceleration sensor 54outputs, to the CPU 100, an acceleration signal representing theacceleration of the main body 10 in three directions orthogonal to oneanother. In this example, the output of the acceleration sensor 54 isused to measure the activity amount.

The communication unit 59 is controlled by the CPU 100 to transmitpredetermined information to an external device through the network, andreceives information from the external device through the network anddelivers the information to the CPU 100. The communication via thenetwork may be either wireless or wired. In this embodiment, the networkis the Internet but it is not limited thereto, and it may be anothertype of network such as a hospital LAN (Local Area Network), or it maybe a one-to-one communication using a USB cable or the like. Thecommunication unit 59 may include a micro USB connector.

The battery 53 is, in this example, configured by a rechargeablesecondary battery. The battery 53 supplies power to elements mounted onthe main body 10, which are, in this example, the CPU 100, the memory51, the acceleration sensor 54, the communication unit 59, the firstpressure sensor 31, the second pressure sensor 32, the pump 30, theopen/close valve 33, and the pump drive circuit 35.

The pump 30 is configured by a piezoelectric pump in this example, andis driven by the pump drive circuit 35 based on a control signal givenfrom the CPU 100. The pump 30 is connected in fluid communication to thepressure cuff 23 via the first flow path formation member 390 and theflexible tube 39, which constitute a first flow path. The pump 30 cansupply air as a pressurizing fluid to the pressure cuff 23 through thefirst flow path formation member 390 and the flexible tube 39. The pump30 is mounted with an unillustrated exhaust valve whose opening andclosing are controlled in accordance with the on/off of the pump 30.That is, the exhaust valve closes when the pump 30 is turned on to helpenclosing of air in the pressure cuff 23, whereas the exhaust valveopens when the pump 30 is turned off to cause the air in the pressurecuff 23 to be discharged to the atmosphere through the flexible tube 39and the first flow path formation member 390. This exhaust valve has afunction of a check valve, and the air to be discharged will never flowback.

The pump 30 is connected in fluid communication to the sensing cuff 21via the second flow path formation member 380 and the flexible tube 38,which constitute a second flow path. The open/close valve (normally opensolenoid valve in this example) 33 is inserted in the second flow path(actually, between the first flow path formation member 390 and thesecond flow path formation member 380). Opening/closing (opening degree)of the open/close valve 33 is controlled based on a control signal givenfrom the CPU 100. When the open/close valve 33 is in the open state, aircan be supplied as a pressure transmission fluid from the pump 30 to thesensing cuff 21 through the second flow path and the sensing cuff 21 iscaused to contain the air.

Each of the first pressure sensor 31 and the second pressure sensor 32is configured by a piezoresistive pressure sensor in this example. Thefirst pressure sensor 31 detects pressure in the pressure cuff 23 viathe first flow path formation member 390 and the flexible tube 39, whichconstitute the first flow path. The second pressure sensor 32 detectspressure in the sensing cuff 21 via the second flow path formationmember 380 and the flexible tube 38, which constitute the second flowpath.

As shown in FIG. 8 (inside of the main body 10 viewed obliquely fromabove), the pump 30 and the first pressure sensor 31 are disposedsubstantially at the center of the inner case member 11 in the main body10. The open/close valve 33 and the second pressure sensor 32 aredisposed around the inner case member 11. As shown in FIG. 9 (inside ofthe main body 10 viewed obliquely from below), the first flow pathformation member 390 is provided on the back side of the inner casemember 11 across a discharge port 30 d of the pump 30, an air inlet 31 dof the first pressure sensor 31, and an inlet 33 i of the open/closevalve 33. The second flow path formation member 380 is disposed on theback side of the inner case member 11 across an outlet 33 e of theopen/close valve 33 and an air inlet 32 d of the second pressure sensor32.

The sphygmomanometer 1 is configured to be compact and integrated bymounting the blood pressure measurement elements described above on themain body 10. Accordingly, the usability for the user is good.

(Operation of Blood Pressure Measurement)

FIG. 11 shows an operation flow when the user performs blood pressuremeasurement using the sphygmomanometer 1 as a blood pressure measurementmethod according to an embodiment of the present invention.

As shown in step S1 of FIG. 11 , the user attaches the sphygmomanometer1 on the left wrist 90 as a measurement target site. At the time of thisattachment, as shown in FIG. 13A, the user first attaches the cuffstructure 20 to the left wrist 90 using a right hand 99 (step S21 inFIG. 12 ). Here, the cuff structure 20 is curved along thecircumferential direction Y of the left wrist 90 by the curler 24 in anatural state. Accordingly, in this example, the user can easily attachthe cuff structure 20 to the left wrist 90 by fitting the cuff structure20 on the outer circumferential surface of the left wrist 90 using thehand (the right hand 99 in this example) on the right side of the body,which is opposite to the left side of the body to which the left wrist90 belongs. With the cuff structure 20 attached to the left wrist 90,the cuff structure 20 holds the left wrist 90 even if the user releasesthe right hand 99 from the cuff structure 20, and hence the cuffstructure 20 (as well as the belt 2 and the main body 10) is unlikely tocome off from the left wrist 90.

Next, as shown in FIG. 13B, the user uses the right hand 99 tocollectively surround the left wrist 90 and the cuff structure 20 withthe belt 2. Specifically, the user passes a portion continuing to thetip end portion 4 f of the second belt portion 4 through the frame 5A ofthe clasp 5 of the first belt portion 3, and inserts the prong 5B of theclasp 5 into any one of the plurality of small holes 4 w, 4 w, . . . ofthe second belt portion 4. Thus, as shown in FIG. 13C, the first beltportion 3 and the second belt portion 4 are fastened (step S22 in FIG.12 ). Due to this, the belt 2 extending from the main body 10 surroundsthe left wrist 90, and the band-shaped cuff structure 20 having the oneend 20 f attached to the main body 10 is disposed on the innercircumferential side closer to the left wrist 90 than the belt 2 is.

Here, in the sphygmomanometer 1, the cuff structure 20 is freelyseparable from the inner circumferential surfaces 3 a and 4 a of thebelt 2, and the other end 20 e on the side opposite to the one end 20 fof the cuff structure 20 is a free end. Accordingly, when fastening thefirst belt portion 3 and the second belt portion 4, the cuff structure20 receives an inward force from the belt 2, and the cuff structure 20can slide or deform so as to exactly follow the outer circumferentialsurface of the left wrist 90. Thus, in the attached state, the cuffstructure 20 and the belt 2 are substantially in close contact in thisorder with the outer circumferential surface of the left wrist 90. Inthis manner, the sphygmomanometer 1 can be easily attached to the leftwrist 90.

Specifically, as shown in FIG. 14 , in this attached state, thebag-shaped pressure cuff 23 extends along the circumferential directionY of the left wrist 90 on the inner circumferential side of the curler24 included in the cuff structure 20. In addition, the bag-shapedsensing cuff 21 included in the cuff structure 20 is disposed on theinner circumferential side of the pressure cuff 23 to be in contact withthe left wrist 90 and extends in the circumferential direction Y acrossan artery passing portion 90 a of the left wrist 90. The back plate 22included in the cuff structure 20 is inserted between the pressure cuff23 and the sensing cuff 21 and extends along the circumferentialdirection Y of the left wrist 90. In FIG. 14 , the main body 10 and thebelt 2 are not illustrated. FIG. 14 shows a radius 93, an ulna 94, aradial artery 91, an ulnar artery 92, and a tendon 96 of the left wrist90.

Next, when the user presses the measurement switch 52A of the operationunit 52 provided in the main body 10 (step S2 in FIG. 11 ), the CPU 100initializes the processing memory area (step S3 in FIG. 11 ). The CPU100 turns off the pump 30 via the pump drive circuit 35, opens theexhaust valve built in the pump 30, and maintains the open/close valve33 in the open state, so that the air in the pressure cuff 23 and thesensing cuff 21 is exhausted. Then, the CPU 100 performs control ofadjusting 0 mmHg of the first pressure sensor 31 and the second pressuresensor 32.

Next, the CPU 100, which serves as a pressurization control unit and afluid containment control unit, turns on the pump 30 via the pump drivecircuit 35 (step S4 in FIG. 11 ), maintains the open/close valve 33 inthe open state, and starts pressurization of the pressure cuff 23 andthe sensing cuff 21 (step S5 in FIG. 11 ). In the pressurizationprocess, the pump 30 is driven via the pump drive circuit 35 whilemonitoring the pressure of the pressure cuff 23 and the sensing cuff 21by the first pressure sensor 31 and the second pressure sensor 32,respectively. As a result, the CPU 100 performs control of sending airto the pressure cuff 23 through the first flow path (the first flow pathformation member 390 and the flexible tube 39) and to the sensing cuff21 through the second flow path (the second flow path formation member380 and the flexibile tube 38).

Next, in step S6 of FIG. 11 , the CPU 100, which serves as a fluidcontainment control unit, determines whether the pressure of the sensingcuff 21 has reached a predetermined pressure (15 mmHg in this example)or whether the driving time of the pump 30 has elapsed a predeterminedlength of time (3 seconds in this example). The reason for making thisdetermination is to confirm whether an appropriate amount of air hasbeen contained in the sensing cuff 21. If NO in step S6 of FIG. 11 , theprocess waits for the pressure of the sensing cuff 21 to reach apredetermined pressure or the driving time of the pump 30 to elapse apredetermined length of time. The amount of an “appropriate amount” ofthe pressure transmission fluid contained in the sensing cuff 21 will bedescribed later.

If YES in step S6 of FIG. 11 , it is determined that an appropriateamount of air has been contained in the sensing cuff 21. Then, in stepS7 of FIG. 11 , the CPU 100, which serves as a pressurization controlunit, closes the open/close valve 33, and continues control of supplyingair from the pump 30 to the pressure cuff 23 through the first flowpath. With this, the pressure cuff 23 is caused to inflate and graduallypressurized to press the left wrist 90. At this time, the back plate 22transmits the pressing force from the pressure cuff 23 to the sensingcuff 21. The sensing cuff 21 presses the left wrist 90 (including theartery passing portion 90 a). In this pressurization process, in orderto calculate the blood pressure value, the CPU 100, using the secondpressure sensor 32, monitors the pressure Pc of the sensing cuff 21,that is, the pressure of the artery passing portion 90 a of the leftwrist 90, and obtains the pulse wave signal Pm as a variation component.FIG. 16 exemplifies the pressure Pc and the waveform of the pulse wavesignal Pm of the sensing cuff 21 obtained in this pressurizationprocess.

Here, FIGS. 15A and 15B schematically show a cross section along thelongitudinal direction of the left wrist 90 (corresponding to the widthdirection X of the cuff) with an appropriate amount of air contained inthe sensing cuff 21 and the open/close valve 33 closed. FIG. 15A shows across section (corresponding to a cross section taken along line XVA-XVAin FIG. 14 ) of a portion through which the tendon 96 of the left wrist90 passes. On the other hand, FIG. 15B shows a cross section(corresponding to a cross section taken along line XVB-XVB in FIG. 14 )of a portion through which the radial artery 91 of the left wrist 90passes. As shown in FIG. 15B, the portion through which the radialartery 91 of the left wrist 90 passes is relatively soft, and hence agap 21 w in which air is present remains between the first sheet 21A andthe second sheet 21B of the sensing cuff 21. Accordingly, a portion ofthe sensing cuff 21 facing the radial artery 91 can reflect the pressureof the artery passing portion 90 a of the left wrist 90. On the otherhand, as shown in FIG. 15A, since the portion through which the tendon96 of the left wrist 90 passes is relatively hard, the first sheet 21Aand the second sheet 21B are in contact with each other in a portioncorresponding to substantially the center of the sensing cuff 21 in thewidth direction X. However, the slacks 21 r and 21 r that extend alongthe longitudinal direction Y (corresponding to the circumferentialdirection of the left wrist 90) as described above are provided at alocation continuing to the edge portions 21 m and 21 m on both sides ofthe sensing cuff 21 in the width direction X, and hence gaps 21 w′ and21 w′ in which air present remain along the longitudinal direction Y. Asa result, the air contained in the sensing cuff 21 can flow along thelongitudinal direction Y of the sensing cuff 21 through the gaps 21 w′and 21 w′. Accordingly, the sensing cuff 21 can successfully transmitthe pressure applied to the artery passing portion 90 a of the leftwrist 90 to the second pressure sensor 32 in the main body 10 as thepressure of air (pressure transmission fluid).

Next, in step S8 of FIG. 11 , the CPU 100, which serves as a bloodpressure calculation unit, attempts to calculate the blood pressurevalue (a systolic blood pressure SBP and a diastolic blood pressure DBP)by applying a publicly known algorithm with the oscillometric methodbased on the pulse wave signal Pm having been acquired at this point oftime.

At this point of time, if the blood pressure value cannot be calculatedbecause of data insufficiency (NO in step S9), the processes of steps S7to S9 are repeated unless the cuff pressure has reached the upper limitpressure (for safety, it is predetermined as 300 mmHg for example).

When the blood pressure value can be calculated (YES in step S9) in thismanner, the CPU 100 performs control of stopping the pump 30 (step S10),opening the open/close valve 33 (step S11), and exhausting the air inthe pressure cuff 23 and the sensing cuff 21. Finally, the measurementresult of the blood pressure value is displayed on the indicator 50(step S12).

The blood pressure calculation may be performed not in thepressurization process but in the depressurization process of thepressure cuff 23.

As described above, in the sphygmomanometer 1, air is contained in thesensing cuff 21 each time the blood pressure is measured, and,separately from the pressure cuff 23, the second pressure sensor 32detects the pressure Pc of the sensing cuff 21, i.e., the pressureitself of the artery passing portion 90 a of the left wrist 90.Accordingly, the blood pressure can be accurately measured, even if thepressure cuff 23 greatly inflates in the thickness direction whenpressurized and press loss occurs as a result of setting the dimensionof the width direction X of the belt 2 and the cuff structure 20 (simplycollectively referred to as “cuff” as appropriate) to be small (about 25mm for example). In the attached state, the sensing cuff 21 extends inthe circumferential direction Y across the artery passing portion 90 aof the left wrist 90. Accordingly, when the user actually attaches thesphygmomanometer 1 on the left wrist 90, the sensing cuff 21 will notcome off from the left wrist 90 at the artery passing portion 90 a evenif the cuff, together with the main body 10, is displaced to a certainextent in the circumferential direction Y of the left wrist 90.Accordingly, it is possible to prevent the blood pressure measurementvalue from varying with respect to the actual blood pressure, and as aresult, it is possible to accurately measure the blood pressure.

While in the above example, the air as the pressure transmission fluidis contained in the sensing cuff 21 each time the blood pressure ismeasured and the air is exhausted after the measurement is completed,the present invention is not limited thereto. The pressure transmissionfluid may be contained and sealed in the sensing cuff 21 at themanufacturing stage of the sphygmomanometer 1.

(Appropriate Amount of Pressure Transmission Fluid Contained in SensingCuff)

FIG. 17 shows a blood pressure measurement error (average value) whenwater is used as the pressure transmission fluid contained in thesensing cuff 21 and the amount of water contained in the sensing cuff 21is set variably. Here, the blood pressure measurement error means adifference obtained by subtracting a blood pressure value measured by astandard (accurate) sphygmomanometer (systolic blood pressure SBP) (thisis called “reference blood pressure value”) from a blood pressure valuemeasured by the sphygmomanometer 1 (systolic blood pressure SBP) for acertain user (subject). That is,(blood pressure measurement error)=(blood pressure value measured bysphygmomanometer 1)−(reference blood pressure value).As can be seen from FIG. 17 , if the amount of water contained in thesensing cuff 21 is within a range wa of 0.26 ml±0.05 ml, the bloodpressure measurement error is within ±5 mmHg, which is considered to bean appropriate amount.

In FIG. 17 , if the amount of water exceeds the appropriate amount rangewa, the blood pressure measurement error increases to the positive side.This is because the water intervening also on the hard portion such asthe tendon 96 in the cross section shown in FIG. 14 raises the internalpressure of the sensing cuff 21 when pressed, and since the portion ofthe left wrist 90 through which the radial artery 91 and the ulnarartery 92 pass is relatively soft, the presence of water in the portionmore than necessary causes the sensing cuff 21 to inflate and theinternal pressure of the sensing cuff 21 increases by the amount of thetension that inflates the sensing cuff 21. In FIG. 17 , when the amountof water falls below the appropriate amount range wa, the blood pressuremeasurement error increases to the negative side. This is consideredbecause the amount of water around the artery becomes too small.

As a result, in this example, the range wa of 0.26 ml±0.05 ml isconsidered to be appropriate for the pressure transmission fluidcontained in the sensing cuff 21. The criteria described above in stepS6 of FIG. 11 for determining whether the pressure of the sensing cuff21 has reached a predetermined pressure (15 mmHg in this example) orwhether the driving time of the pump 30 has elapsed a predeterminedlength of time (3 seconds in this example) has been set so as to satisfythe condition that the amount of air as a pressure transmission fluidcontained in the sensing cuff 21 falls within the range wa of 0.26ml±0.05 ml.

As a matter of course, the appropriate amount of the pressuretransmission fluid contained in the sensing cuff 21 depends on the sizeof the sensing cuff 21 and the like.

(Verification Result)

The scatter diagram in FIG. 18 shows a relationship between thereference blood pressure value and the blood pressure measurement errorin the case where the amount of water as a pressure transmission fluidcontained in the sensing cuff 21 is set variably to “small amount ofwater”=0.16 ml, “appropriate amount”=0.3 ml, and “large amount ofwater”=0.8 ml for a plurality of users (in this example, measurement isperformed three times for each of five subjects whose systolic bloodpressure SBP is from 97 mmHg to 149 mmHg). If the amount of water is the“appropriate amount”, the blood pressure measurement error is small forthe plurality of users as shown by the square mark (□) in the figure. Onthe other hand, in case of the “large amount of water”, the bloodpressure measurement error is large to the positive side for theplurality of users as shown by the cross mark (x) in the figure. In caseof the “small amount of water”, the blood pressure measurement error islarge on the negative side for the plurality of users as shown by therhomboid mark (⋄) in the figure.

This verification result indicates that according to thesphygmomanometer 1 of the present invention, the blood pressure can bemeasured accurately even if the dimension of the width direction X ofthe cuff is set small (in this example, the substantial width directiondimension of the sensing cuff 21 is W4=15 mm, and the substantial widthdirection dimension of the pressure cuff 23 is set to W2=25 mm).

In particular, when a plurality of users each actually attach thesphygmomanometer 1 on the left wrist 90 to measure the blood pressure,for some users, the cuff, together with the main body 10, may bedisplaced to a certain extent in the circumferential direction Y of theleft wrist 90. Here, in the verification result of FIG. 18 , if theamount of water is appropriate, the blood pressure measurement errorsare suppressed for the plurality of users. Accordingly, it can beconfirmed that with this sphygmomanometer 1, the blood pressure can bemeasured accurately even if the cuff, together with the main body 10, isdisplaced to a certain extent in the circumferential direction Y of theleft wrist 90.

While in the embodiment described above, the example in which thesensing cuff 21 is in direct contact with the left wrist 90 as themeasurement target site has been described, the present invention is notlimited thereto. The sensing cuff 21 may come into contact with the leftwrist 90 indirectly via another member (cover member for example).

In the embodiment described above, the measurement target site to whichthe sphygmomanometer is mounted is the left wrist 90. However, thepresent invention is not limited thereto. The sphygmomanometer accordingto the present invention may be configured to be optically symmetricalwith respect to the sphygmomanometer 1 shown in FIGS. 1 and 2 andattached to the right wrist. The measurement target site may be a siteother than the wrist, such as an upper arm or a lower leg.

In the embodiment described above, the main body 10 and the belt 2 areformed separately from each other, and the belt 2 is attached to themain body 10. However, the present invention is not limited thereto. Themain body 10 and the belt 2 may be integrally molded.

In the embodiment described above, the first belt portion 3 and thesecond belt portion 4 of the belt 2 are fastened or released by theclasp 5. However, the present invention is not limited thereto. Forexample, the first belt portion 3 and the second belt portion 4 may becoupled to each other via an openable three-fold buckle.

In the embodiment described above, the CPU 100 mounted on thesphygmomanometer 1 serves as a fluid containment control unit, apressurization control unit, and a blood pressure calculation unit, andexecutes blood pressure measurement (operation flow in FIG. 11 ).However, the present invention is not limited thereto. A substantialcomputer device such as a smartphone provided outside thesphygmomanometer 1, for example, serves as a fluid containment controlunit, a pressurization control unit, and a blood pressure calculationunit, and may cause the sphygmomanometer 1 to execute blood pressuremeasurement (operation flow in FIG. 11 ) via a network 900.

As described above, a sphygmomanometer of the present disclosureincludes:

a main body mounted with a pump;

a belt that extends from the main body and is to be attached around ameasurement target site; and

a cuff structure having a band shape, and that is disposed facing aninner circumferential surface of the belt and has one end attached tothe main body in a freely separable manner from the innercircumferential surface of the belt,

wherein the cuff structure includes

a bag-shaped pressure cuff that extends along a circumferentialdirection of the measurement target site so as to receive a supply ofpressurization fluid to press the measurement target site,

a sensing cuff that is configured in a bag shape so as to be capable ofcontaining pressure transmission fluid, is disposed along an innercircumferential surface of the pressure cuff, and extends in thecircumferential direction across an artery passing portion of themeasurement target site, and

a back plate that is inserted between the pressure cuff and the sensingcuff, extends along the circumferential direction of the measurementtarget site, and transmits a pressing force from the pressure cuff tothe sensing cuff, and

the sphygmomanometer includes

a pressurization control unit that performs control of supplying thepressurization fluid from the pump to the pressure cuff to press themeasurement target site, and

a blood pressure calculation unit that calculates a blood pressure basedon a pressure of the pressure transmission fluid contained in thesensing cuff.

As for the “belt” that “extends from the main body” in the presentspecification, the main body and the belt may be integrally molded, orthe main body and the belt may be formed separately from each other andthe belt may be attached to the main body. Furthermore, as for the beltitself, a first belt portion that extends in one direction from the mainbody and a second belt portion that extends in the other direction fromthe main body may be fastened or released by a clasp, or may be coupledby an openable buckle. The “inner circumferential surface” of the beltrefers to a surface that is on the inner circumferential side with thebelt being attached around the measurement target site. Similarly, the“inner circumferential surface” of the pressure cuff refers to a surfacethat is on the inner circumferential side with the pressure cuff beingattached around the measurement target site.

In addition, the “pressure transmission fluid” may be contained in thesensing cuff at the manufacturing stage of the sphygmomanometer, or mayalso be contained in the sensing cuff and discharged from the sensingcuff each time the blood pressure is measured.

Also, the “fluid” for pressurization or pressure transmission istypically air, but it may be other gas or liquid.

In the sphygmomanometer according to the present disclosure, the beltextending from the main body surrounds the measurement target site, andthe band-shaped cuff structure having one end attached to the main bodyis attached on the measurement target site while disposed on the innercircumferential side closer to the measurement target site than the beltis. In this attached state, the bag-shaped pressure cuff included in thecuff structure extends along the circumferential direction of themeasurement target site. In addition, the bag-shaped sensing cuffincluded in the cuff structure is disposed more on the innercircumferential side than the pressure cuff is and extends in thecircumferential direction across an artery passing portion of themeasurement target site. The back plate included in the cuff structureis inserted between the pressure cuff and the sensing cuff and extendsalong the circumferential direction of the measurement target site.

At the time of blood pressure measurement, for example, a pressuretransmission fluid is first contained in the sensing cuff. In thatstate, the pressurization control unit performs control of supplying thepressurization fluid from the pump mounted on the main body to thepressure cuff to press the measurement target site. At this time, theback plate transmits the pressing force from the pressure cuff to thesensing cuff. The sensing cuff presses the measurement target site(including the artery passing portion). The blood pressure calculationunit calculates the blood pressure based on the pressure of the pressuretransmission fluid contained in the sensing cuff in the pressurizationprocess or the depressurization process of the pressure cuff(oscillometric method).

Here, in this sphygmomanometer, the sensing cuff detects the pressureitself applied to an artery passing portion of the measurement targetsite. Accordingly, the blood pressure can be accurately measured, evenif the pressure cuff greatly inflates in the thickness direction whenpressurized and press loss occurs as a result of setting the widthdirection dimension of the belt and the cuff structure (the belt and thecuff structure are collectively referred to as “cuff” as appropriate) tobe small (about 25 mm for example). In addition, in the attached state,the sensing cuff extends in the circumferential direction across anartery passing portion of the measurement target site. Accordingly, whenthe user actually attaches the sphygmomanometer on the measurementtarget site, the sensing cuff will not come off from an artery passingportion of the measurement target site even if the cuff, together withthe main body, is displaced to a certain extent in the circumferentialdirection of the measurement target site. Accordingly, it is possible toprevent the blood pressure measurement value from varying with respectto the actual blood pressure, and as a result, it is possible toaccurately measure the blood pressure.

Since the cuff structure is freely separable from the innercircumferential surface of the belt and is not attached to the belt, thedimension of the cuff structure in the longitudinal direction(corresponding to the circumferential direction of the measurementtarget site) can be set to the optimum dimension regardless of the belt.

It is desirable that the belt is made of a material that has flexibilityin the thickness direction of the belt and exhibits substantially nostretchability in the longitudinal direction of the belt (correspondingto the circumferential direction of the measurement target site). Thisallows the belt to be easily wrapped around and restrain the outercircumferential side of the cuff structure at the time of attachment,and to help pressing the measurement target site at the time of bloodpressure measurement.

In the sphygmomanometer according to one embodiment, the cuff structureincludes, along an outer circumferential surface of the pressure cuff, acurler for keeping a shape of the cuff structure in a natural statecurved along the circumferential direction of the measurement targetsite.

In the present specification, a “curler” refers to a member that istypically formed of a resin plate having a certain degree of flexibilityand hardness and has a shape curved along the circumferential directionsurrounding the measurement target site in a natural state.

The sphygmomanometer according to this embodiment facilitates attachmenton the measurement target site. That is, at the time of attachment, theuser first attaches the cuff structure to the measurement target site(for example, the left wrist) (a first step of attaching). Here, sincethe cuff structure is curved along the circumferential direction of themeasurement target site by the curler in a natural state, the user caneasily attach the cuff structure on the measurement target site byfitting the cuff structure on the outer circumferential surface of themeasurement target site using the hand (the right hand in this example)on one side of the body, which is opposite to the side of the body towhich the measurement target site (left wrist in this example) belongs.With the cuff structure attached to the measurement target site, thecuff structure holds the measurement target site even if the userreleases the hand (the right hand in this example) from the cuffstructure, and hence the cuff structure (as well as the belt and themain body) is unlikely to come off from the measurement target site.Next, the user uses the hand (the right hand in this example) tocollectively surround the measurement target site and the cuff structurewith the belt (a second step of attaching). Thus, the sphygmomanometerof this embodiment can be easily attached to the measurement targetsite.

In the sphygmomanometer according to one embodiment, a basal portion onthe main body side of the curler that forms the one end of the cuffstructure is clamped between a member provided in the main body and aback lid of the main body, and thus the one end of the cuff structure isattached to the main body.

In the sphygmomanometer according to this embodiment, a basal portion ofthe curler on the main body side, which forms the one end of the cuffstructure, is clamped between a member provided in the main body and aback lid of the main body. Due to this, the one end of the cuffstructure is attached to the main body. Accordingly, the one end of thecuff structure is reliably held by the main body. At the time ofmaintenance service, the cuff structure can be replaced with respect tothe main body regardless of the belt by opening the back lid of the mainbody.

If the main body and the belt are formed separately from each other andthe belt is attached to the main body, the belt can be replaced withrespect to the main body regardless of the cuff structure at the time ofmaintenance service.

In the sphygmomanometer according to one embodiment, the other end ofthe cuff structure on a side opposite to the one end is a free end.

In the sphygmomanometer according to this embodiment, the cuff structureis freely separable from the inner circumferential surface of the belt,and the other end of the cuff structure on a side opposite to the oneend is a free end. Therefore, when the user collectively surrounds themeasurement target site and the cuff structure with the belt (the secondstep of attaching), the cuff structure receives an inward force from thebelt, and the cuff structure can slide or deform so as to exactly followthe outer circumferential surface of the measurement target site. Thus,in the attached state, the cuff structure and the belt are substantiallyin close contact in this order with the outer circumferential surface ofthe measurement target site. As a result, blood pressure can be measuredaccurately.

In the sphygmomanometer according to one embodiment,

the back plate extends in a band shape beyond a length of the sensingcuff in the circumferential direction of the measurement target site,and

the back plate has a plurality of grooves with V-shaped or U-shapedcross sections that extend in a width direction of the back plate andare parallel to and spaced apart from each other in a longitudinaldirection of the back plate so that the back plate can be curved alongthe circumferential direction of the measurement target site.

In the sphygmomanometer according to this embodiment, the back plateextends in a band shape beyond the length of the sensing cuff in thecircumferential direction of the measurement target site. Accordingly,the back plate can transmit the pressing force from the pressure cuff tothe entire area in the longitudinal direction of the sensing cuff(corresponding to the circumferential direction of the measurementtarget site). The back plate has a plurality of grooves with V-shaped orU-shaped cross sections that extend in the width direction of the backplate and are parallel to and spaced apart from each other in thelongitudinal direction of the back plate so that the back plate can becurved along the circumferential direction of the measurement targetsite. Due to this, the back plate does not obstruct the cuff structurefrom being bent along the circumferential direction of the measurementtarget site when the user collectively surrounds the measurement targetsite and the cuff structure with the belt (the second step of attaching)at the time of attaching.

In the sphygmomanometer according to one embodiment,

the sensing cuff includes a first sheet on a side in contact with themeasurement target site and a second sheet facing the first sheet, andcircumferential portions of the first and second sheets are brought intoclose contact with each other to form the bag shape, and

a slack that extends in a longitudinal direction of the sensing cuff ina natural state is provided on the first or second sheet at a locationcontinuing to edge portions on both sides of the sensing cuff in a widthdirection.

In the present specification, “contact” includes not only direct contactbut also indirect contact via another member (for example, a covermember).

The “slack” of the first or second sheet of the sensing cuff can beformed, for example, when the circumferential portions of the first andsecond sheets are welded together so as to be brought into closecontact.

In the sphygmomanometer according to this embodiment, a slack thatextends in the longitudinal direction of the sensing cuff in a naturalstate is provided on the first or second sheet at a location continuingto the edge portions on both sides of the sensing cuff in the widthdirection. Accordingly, even if the first and second sheets of thesensing cuff are clamped between the pressure cuff (and the back plate)and the measurement target site and come into contact with each otherwhen the pressure cuff is pressurized, a gap that extends along thelongitudinal direction of the sensing cuff (corresponding to thecircumferential direction of the measurement target region) remains at alocation continuing to the edge portions on both sides in the widthdirection of the sensing cuff due to the slack. As a result, thepressure transmission fluid contained in the sensing cuff can flow alongthe longitudinal direction of the sensing cuff through the gap.Accordingly, the sensing cuff can successfully transmit the pressureapplied to an artery passing portion of the measurement target site tothe blood pressure calculation unit as the pressure of the pressuretransmission fluid.

The sphygmomanometer according to one embodiment comprises a fluidcontainment control unit that performs control of supplying the pressuretransmission fluid from the pump to the sensing cuff and causes thesensing cuff to contain the pressure transmission fluid in an attachedstate where the belt and the cuff structure together with the main bodyare attached to the measurement target site.

In the sphygmomanometer according to this embodiment, the fluidcontainment control unit performs control of supplying the pressuretransmission fluid from the pump to the sensing cuff and causes thesensing cuff to contain the pressure transmission fluid in the attachedstate. Accordingly, the pressure transmission fluid can be contained inthe sensing cuff each time blood pressure is measured. When the bloodpressure measurement is completed, the pressure transmission fluid maybe discharged from the sensing cuff.

In the sphygmomanometer according to one embodiment,

the main body is mounted with

a first flow path that connects in fluid communication the pump and thepressure cuff, and

a second flow path that connects in fluid communication the pump or thefirst flow path and the sensing cuff and has an open/close valveinserted therein,

the fluid containment control unit opens the open/close valve, in theattached state, and supplies the pressure transmission fluid from thepump or the first flow path to the sensing cuff through the second flowpath and causes the sensing cuff to contain the pressure transmissionfluid, and

after the pressure transmission fluid is contained in the sensing cuff,the pressurization control unit closes the open/close valve and suppliesthe pressurization fluid from the pump to the pressure cuff through thefirst flow path to press the measurement target site.

In the sphygmomanometer of this embodiment, the pressure transmissionfluid can be supplied to and contained in the sensing cuff with a simpleconfiguration. With the pressure transmission fluid contained and sealedin the sensing cuff, the pressurization fluid can be supplied to thepressure cuff, and pressurization can be carried out.

In the sphygmomanometer according to one embodiment, the main body ismounted with the pressurization control unit, the blood pressurecalculation unit, and the fluid containment control unit.

The sphygmomanometer of this embodiment can be configured to be compactand integrated. Accordingly, the usability for the user is good.

In another aspect, a blood pressure measurement method of the presentdisclosure is a method for measuring a blood pressure at a measurementtarget site, including:

a main body mounted with a pump;

a belt that extends from the main body and is to be attached around ameasurement target site; and

a cuff structure having a band shape, and that is disposed facing aninner circumferential surface of the belt and has one end attached tothe main body in a freely separable manner from the innercircumferential surface of the belt,

wherein the cuff structure includes

a bag-shaped pressure cuff that extends along a circumferentialdirection of the measurement target site so as to receive a supply ofpressurization fluid to press the measurement target site,

a sensing cuff that is configured in a bag shape so as to be capable ofcontaining pressure transmission fluid, is disposed along an innercircumferential surface of the pressure cuff, and extends in thecircumferential direction across an artery passing portion of themeasurement target site, and

a back plate that is inserted between the pressure cuff and the sensingcuff, extends along the circumferential direction of the measurementtarget site, and transmits a pressing force from the pressure cuff tothe sensing cuff,

the blood pressure measurement method comprising:

performing control of supplying the pressurization fluid from the pumpto the pressure cuff to press the measurement target site, and

calculating a blood pressure based on a pressure of the pressuretransmission fluid contained in the sensing cuff

According to the blood pressure measurement method of the presentdisclosure, for example, the pressure transmission fluid is firstcontained in the sensing cuff in the attached state where the beltextending from the main body surrounds the measurement target site, andthe band-shaped cuff structure having one end attached to the main bodyis closer to the measurement target site than the belt is. In thatstate, the pressurization fluid is supplied from the pump mounted on themain body to the pressure cuff to perform control of pressing themeasurement target site. At this time, the back plate transmits thepressing force from the pressure cuff to the sensing cuff. The sensingcuff presses the measurement target site (including the artery passingportion). Then, the blood pressure is calculated based on the pressureof the pressure transmission fluid contained in the sensing cuff(oscillometric method).

Here, the sensing cuff detects the pressure itself applied to an arterypassing portion of the measurement target site. Accordingly, the bloodpressure can be accurately measured, even if the pressure cuff greatlyinflates in the thickness direction when pressurized and press lossoccurs as a result of setting the width direction dimension of the cuffto be small (about 25 mm for example). In addition, in the attachedstate, the sensing cuff extends in the circumferential direction acrossan artery passing portion of the measurement target site. Accordingly,when the user actually attaches the sphygmomanometer on the measurementtarget site, the sensing cuff will not come off from an artery passingportion of the measurement target site even if the cuff, together withthe main body, is displaced to a certain extent in the circumferentialdirection of the measurement target site. Accordingly, it is possible toprevent the blood pressure measurement value from varying with respectto the actual blood pressure, and as a result, it is possible toaccurately measure the blood pressure.

In another aspect, a device of the present disclosure is a devicecomprising a main body mounted with blood pressure measurement elements,

wherein the blood pressure measurement elements include

a pump mounted to the main body,

a belt that extends from the main body and is to be attached around ameasurement target site, and

a cuff structure having a band shape, and that is disposed facing aninner circumferential surface of the belt and has one end attached tothe main body in a freely separable manner from the innercircumferential surface of the belt,

the cuff structure includes

a bag-shaped pressure cuff that extends along a circumferentialdirection of the measurement target site so as to receive a supply ofpressurization fluid to press the measurement target site,

a sensing cuff that is configured in a bag shape so as to be capable ofcontaining pressure transmission fluid, is disposed along an innercircumferential surface of the pressure cuff, and extends in thecircumferential direction across an artery passing portion of themeasurement target site, and

a back plate that is inserted between the pressure cuff and the sensingcuff, extends along the circumferential direction of the measurementtarget site, and transmits a pressing force from the pressure cuff tothe sensing cuff, and

the device includes

a pressurization control unit that performs control of supplying thepressurization fluid from the pump to the pressure cuff to press themeasurement target site, and

a blood pressure calculation unit that calculates a blood pressure basedon a pressure of the pressure transmission fluid contained in thesensing cuff.

The “device” of the present disclosure widely includes a device having ablood pressure measurement function, and may be configured as, forexample, a wristwatch-type wearable device such as a smart watch.

According to the device of the present disclosure, the blood pressuremeasurement value can be prevented from varying with respect to theactual blood pressure, and as a result, the blood pressure can bemeasured accurately.

As is apparent from the above, according to the sphygmomanometer, theblood pressure measurement method, and the device of the presentdisclosure, it is possible to accurately measure blood pressure whilepermitting a certain degree of displacement of the cuff in thecircumferential direction of the measurement target site.

The above embodiments are illustrative, and are modifiable in a varietyof ways without departing from the scope of this invention. It is to benoted that the various embodiments described above can be appreciatedindividually within each embodiment, but the embodiments can be combinedtogether. It is also to be noted that the various features in differentembodiments can be appreciated individually by its own, but the featuresin different embodiments can be combined.

The invention claimed is:
 1. A sphygmomanometer comprising: a main bodymounted with a pump; a belt that extends respectively from oppositesides of the main body and is to be attached around a measurement targetsite; a cuff structure having a band shape, a first end of the cuffstructure being attached to the main body, the cuff structure including:a bag-shaped pressure cuff that extends along a circumferentialdirection of the measurement target site so as to receive a supply ofpressurization fluid to press the measurement target site, a sensingcuff that is configured in a bag shape so as to be configured to containpressure transmission fluid, is disposed along an inner circumferentialsurface of the pressure cuff, and extends in the circumferentialdirection across an artery passing portion of the measurement targetsite, and a back plate that is inserted between the pressure cuff andthe sensing cuff, extends along the circumferential direction of themeasurement target site, and transmits a pressing force from thepressure cuff to the sensing cuff, wherein in a state that thesphygmomanometer has been assembled, the cuff structure is disposedfacing an inner circumferential surface of the belt and is affixed onlyto the main body only at the first end in a separable manner from theinner circumferential surface of the belt; and a programmed processorthat acts as: a pressurization control unit to perform control ofsupplying the pressurization fluid from the pump to the pressure cuff topress the measurement target site, and a blood pressure calculation unitto calculate a blood pressure based on a pressure of the pressuretransmission fluid contained in the sensing cuff, wherein the beltextending respectively from the opposite sides of the main body isconfigured to surround and restrain, in the circumferential direction,an outer circumferential side of the cuff structure extending along thecircumferential direction of the measurement target site collectivelywith the measurement target site, in an attached state where the beltand the cuff structure together with the main body are attached to themeasurement target site, such that the pressure cuff of the cuffstructure presses the measurement target site.
 2. The sphygmomanometeraccording to claim 1, wherein the cuff structure includes, along anouter circumferential surface of the pressure cuff, a curler configuredto maintain a shape of the cuff structure in a natural state curvedalong the circumferential direction of the measurement target site. 3.The sphygmomanometer according to claim 2, wherein: the curler isconfigured to extend in a band shape from a basal portion located on themain body side to a tip end portion on a side opposite to the basalportion along the circumferential direction of the measurement targetsite, and the basal portion of the curler is clamped, as the first endof the cuff structure, between an inner case member provided in the mainbody and a back lid of the main body, and thus the first end of the cuffstructure is attached to the main body.
 4. The sphygmomanometeraccording to claim 1, wherein in the state that the sphygmomanometer hasbeen assembled, a second end of the cuff structure on a side opposite tothe first end is a free end.
 5. The sphygmomanometer according to claim1, wherein: the back plate extends in a band shape beyond a length ofthe sensing cuff in the circumferential direction of the measurementtarget site, and the back plate has a plurality of grooves with V-shapedor U-shaped cross sections that extend in a width direction of the backplate and are parallel to and spaced apart from each other in alongitudinal direction of the back plate so that the back plate isconfigured to be curved along the circumferential direction of themeasurement target site.
 6. The sphygmomanometer according to claim 1,wherein: the sensing cuff includes a first sheet on a side in contactwith the measurement target site and a second sheet facing the firstsheet, and circumferential portions of the first and second sheets arebrought into close contact with each other to form the bag shape, and aslack that extends in a longitudinal direction of the sensing cuff in anatural state is provided on the first or second sheet at a locationcontinuing to edge portions on both sides of the sensing cuff in a widthdirection.
 7. The sphygmomanometer according to claim 1, wherein theprogrammed processor acts as a fluid containment control unit to performcontrol of supplying the pressure transmission fluid from the pump tothe sensing cuff and cause the sensing cuff to contain the pressuretransmission fluid in the attached state.
 8. The sphygmomanometeraccording to claim 7, wherein the main body is mounted with: a firstflow path that connects in fluid communication with the pump and thepressure cuff, and a second flow path that connects in fluidcommunication with the pump or the first flow path and the sensing cuffand has an open/close valve inserted therein, the fluid containmentcontrol unit opens the open/close valve, in the attached state, andsupplies the pressure transmission fluid from the pump or the first flowpath to the sensing cuff through the second flow path and causes thesensing cuff to contain the pressure transmission fluid, and after thepressure transmission fluid is contained in the sensing cuff, thepressurization control unit closes the open/close valve and supplies thepressurization fluid from the pump to the pressure cuff through thefirst flow path to press the measurement target site.
 9. Thesphygmomanometer according to claim 7, wherein the main body is mountedwith the programmed processor.
 10. The sphygmomanometer according toclaim 1, wherein: the cuff structure has a set length extending from thefirst end to a second end on a side opposite to the first end, and alength of the belt along the circumferential direction is configured tobe set variably depending on the measurement target site.
 11. Thesphygmomanometer according to claim 10, wherein the belt includes: afirst belt portion that extends from a first side of the main body; asecond belt portion that extends from a second side opposite to thefirst side of the main body; and a clasp or a buckle that is configuredto couple the first belt portion to the second belt portion in a mannerwhere the length of the belt along the circumferential direction is setvariably depending on the measurement target site.
 12. Thesphygmomanometer according to claim 1, wherein in a state that thesphygmomanometer has been assembled and before being attached to themeasurement target site, the cuff structure is exposed to be movablerelative to the belt.
 13. A blood pressure measurement method formeasuring a blood pressure at a measurement target site using asphygmomanometer, the sphygmomanometer including: a programmedprocessor; a main body mounted with a pump; a belt that extendsrespectively from opposite sides of the main body and is to be attachedaround the measurement target site; and a cuff structure having a bandshape, a first end of the cuff structure being attached to the mainbody, the cuff structure including: a bag-shaped pressure cuff thatextends along a circumferential direction of the measurement target siteso as to receive a supply of pressurization fluid to press themeasurement target site, a sensing cuff that is configured in a bagshape so as to be configured to contain pressure transmission fluid, isdisposed along an inner circumferential surface of the pressure cuff,and extends in the circumferential direction across an artery passingportion of the measurement target site, and a back plate that isinserted between the pressure cuff and the sensing cuff, extends alongthe circumferential direction of the measurement target site, andtransmits a pressing force from the pressure cuff to the sensing cuff,wherein in a state that the sphygmomanometer has been assembled, thecuff structure is disposed facing an inner circumferential surface ofthe belt and is affixed only to the main body only at the first end in aseparable manner from the inner circumferential surface of the belt, andwherein the belt extending respectively from the opposite sides of themain body is configured to surround and restrain, in the circumferentialdirection, an outer circumferential side of the cuff structure extendingalong the circumferential direction of the measurement target sitecollectively with the measurement target site, in an attached statewhere the belt and the cuff structure together with the main body areattached to the measurement target site, such that the pressure cuff ofthe cuff structure presses the measurement target site, the bloodpressure measurement method comprising: performing, by the programmedprocessor, control of supplying the pressurization fluid from the pumpto the pressure cuff to press the measurement target site, andcalculating, by the programmed processor, a blood pressure based on apressure of the pressure transmission fluid contained in the sensingcuff.
 14. A device comprising a main body mounted with blood pressuremeasurement elements, the blood pressure measurement elements including:a pump mounted to the main body, a belt that extends respectively fromopposite sides of the main body and is to be attached around ameasurement target site, and a cuff structure having a band shape, afirst end of the cuff structure being attached to the main body, thecuff structure including: a bag-shaped pressure cuff that extends alonga circumferential direction of the measurement target site so as toreceive a supply of pressurization fluid to press the measurement targetsite, a sensing cuff that is configured in a bag shape so as to beconfigured to contain pressure transmission fluid, is disposed along aninner circumferential surface of the pressure cuff, and extends in thecircumferential direction across an artery passing portion of themeasurement target site, and a back plate that is inserted between thepressure cuff and the sensing cuff, extends along the circumferentialdirection of the measurement target site, and transmits a pressing forcefrom the pressure cuff to the sensing cuff, wherein in a state that thedevice has been assembled, the cuff structure is disposed facing aninner circumferential surface of the belt and is affixed only to themain body only at the first end in a separable manner from the innercircumferential surface of the belt, and wherein the belt extendingrespectively from the opposite sides of the main body is configured tosurround and restrain, in the circumferential direction, an outercircumferential side of the cuff structure extending along thecircumferential direction of the measurement target site collectivelywith the measurement target site, in an attached state where the beltand the cuff structure together with the main body are attached to themeasurement target site, such that the pressure cuff of the cuffstructure presses the measurement target site, and the device includes aprogrammed processor that acts as: a pressurization control unit toperform control of supplying the pressurization fluid from the pump tothe pressure cuff to press the measurement target site, and a bloodpressure calculation unit to calculate a blood pressure based on apressure of the pressure transmission fluid contained in the sensingcuff.